Washing Machine Drain Hose Backup at Drainpipe - Video

[David Lyell]

As shown in the attached video, when draining, water backs up from where the drainpipe and drain hose are connected. Also, there is a small gap between the drainhose and drainpipe (my understanding is there needs to be a gap to prevent a vacuum from forming).
Prior to this video being recorded, I inserted a garden hose into the drainpipe, and eventually ran it at full blast, and there was no water backup.
Which is why this video has me baffled.
I don't think the drainpipe itself is clogged, as it can discharge water from a garden hose at full blast.
So why is it backing up when the washing machine empties itself into the drainpipe? Any ideas on how to fix this, please?
Since shooting the video, I have the washing machine unplugged, and have been using towels, fans, and a wet/dry vac to clean the affected area beneath the washing machine.

If you have any advice, and/or can point me in the right direction on how I can fix this problem, I'd really appreciate it. Thanks.
Video:

 

[Jeff H Young]

Id say you cleared the stoppage its not plugged anymore. Try running the machine again
In any case if water does not drain there is a stoppage real simple. its possible full blast on hose bib is slower than the pump if its not better. run a snake down

 

[Sponsor]

 

[Reach4]

run a snake down

Agree. A big-enough one.

Also, how high is your standpipe above the trap? Your code allows up to 30 inches, but IPC allows up to 42 inches. You could try extending your standpipe. You could just press the coupling and pipe on to make it easy to remove. Your overflow is not subtle. Maybe get a pro to rod your pipes.

A bigger diameter but shorter garden hose could help your testing, but will not solve the problem.

As shown in the attached video, when draining, water backs up from where the drainpipe and drain hose are connected. Also, there is a small gap between the drainhose and drainpipe (my understanding is there needs to be a gap to prevent a vacuum from forming).

You certainly are not having a vacuum forming. I think a washing machine does not need an air gap, because that is built in. But more air space will not make your water flow better.

 

[wwhitney]

If, when inserted the same amount in the standpipe, the washing machine causes a backup but the garden hose doesn't (for comparable flow times and starting conditions), then the washing machine must be pumping out water faster than the garden hose.

Is it possible that the standpipe itself has a restriction, and that with the garden hose, you inserted it down farther, past the restriction?

Cheers, Wayne

 

[WorthFlorida]

The washing machine is dumping more water than the garden hose. A garden hose is maybe 5/8" in diameter and the machine discharge is at least 1". It appears you have 1.5" galvanized pipe and over time they build up with scale and rust. This is the very reason why the code was changed to 2" drain lines. When the water is pumped from the machine, the air in the drain pipe is pushed out and up to the roof vent. This doesn't look like it is happening. With the garden hose there is enough space around the water slug to for air to get around it and out the top of the stand pipe.

If this problem started recently I would check out the vent. At the tee there could be loaded with lint limited the amount if air entering the drain or a critter or bird fell in the pipe and its plugged up. If the vent goes straight up to the roof, run the garden hose from the roof into the vent pipe to flush out any debris. A plumbing auger (not a snake) may be needed to scrape the inside of the pipe.

 

[Jeff H Young]

stoppage